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题名	基于导电聚合物和纳米材料的固态离子选择性电极的研究
作者	尹坦姬
学位类别	博士
答辩日期	2015-04
授予单位	中国科学院研究生院
授予地点	北京
导师	秦伟
关键词	导电聚合物 纳米材料 固体接触传导层 固态离子选择性电极
学位专业	环境科学
中文摘要	相比较于传统内充液式离子选择性电极，固态离子选择性电极因其没有内充液的存在，可以有效避免从电极膜相流向样品溶液相的稳态主离子通量带来的影响，且不需要特别维护保养、更加持久耐用、易于小型化、在测量时可以随意方位放置电极无需考虑内充液渗漏等问题，在发展环境分析监测方法和监测技术方面具有广阔的应用前景。然而，受离子选择性敏感膜与导电基体界面间电子转移阻抗、双电层电容和水层的影响，固态离子选择性电极的长期电位稳定性困扰着其长远发展。此外，离子选择性敏感膜组分，尤其是离子载体的缓慢渗漏以及实际样品测定时亲脂性物质的干扰同样会限制其广泛使用。基于此，本论文从解决固态聚合物膜离子选择性电极的电位稳定性问题、离子载体渗漏问题、实际样品测定时亲脂性物质干扰问题三方面开展了一系列研究工作。具体研究内容如下： 1. 利用和改善已有的导电聚合物固体接触传导层 导电聚合物作为一种具有导电性能的高分子聚合物，它可以通过电聚合单体或者溶液浇铸方式沉积在碳、金或者铂等导电基体上，形成欧姆接触层。此外，导电聚合物是具有良好离子和电子传导性能的电活性材料，在传导过程中可以将离子信号转换为电信号。基于这些独特的性质，导电聚合物被广泛用作固态离子选择性电极的离子–电子传导层。 (1) 聚吡咯导电聚合物的物理化学性质受不同掺杂离子种类的影响很大，其中Nafion掺杂的聚吡咯，与其他离子掺杂的聚吡咯(如ClO4-)相比，具有良好的机械强度和电化学稳定性。基于此，将Nafion掺杂聚吡咯作为离子–电子传导层发展了固态聚合物膜Pb2+离子选择性电极。Nafion的使用不仅改善已有聚吡咯固体接触传导层的性能，包括氧化还原电容和电极粘附性，并且基于其疏水性骨架能有效排除固体接触传导层与离子选择性敏感膜界面间水层对电极电位的影响。发展的固态Pb2+离子选择性电极线性响应范围为1.0×10-7 - 1.0×10-3 M，检出限为4.3×10-8 M，响应时间小于10 s。该电极具有良好的电位稳定性，并且未发现明显水层影响。 (2) 聚3-辛基噻吩(POT)是一类具有高氧化电位的导电聚合物，与聚吡咯相比，它具有低的电化学活性、低的电子传导性和低的氧化还原电容，因此，它不会像高p型掺杂聚吡咯导电聚合物一样参与副反应。另外，POT具有较高的亲脂性，它能有效阻止导电基体与离子选择性敏感膜之间水层的存在。此外，由于本身聚合物骨架上硫原子和双键的存在，POT能选择性地识别Ag+。基于此，将POT与Ag+离子选择性敏感膜均相混合后滴涂在电极上制备了固态聚合物膜Ag+离子选择性电极。POT的使用不仅与Ag+离子载体共同作用识别Ag+，还利用其作为离子–电子传导层提高固态离子选择性电极的稳定性。发展的单片固态聚合物膜Ag+离子选择性电极线性响应范围为3.0×10-8 - 3.0×10-5 M，检出限为1.9×10-8 M。该电极具有良好的电位稳定性，未发现氧化还原物质干扰和水层的影响。该电极可用于Cl-电位滴定和加标水样中Ag+的测定。 2. 发展新的纳米材料固体接触传导层 导电聚合物，包括聚吡咯、聚3-辛基噻吩和聚3，4-乙烯二氧基噻吩及其衍生物，被广泛用作固态离子选择性电极的离子–电子传导层。然而，该类型固体接触传导层在传导过程中容易受光照、电聚合时残留的盐类、与氧化还原干扰物质、O2或CO2发生电化学副反应等影响。纳米材料，包括富勒烯､三维有序大孔碳､碳纳米管､石墨烯､金纳米簇等，具有大的比表面积、良好的传导性和疏水性等特点，近年来被用作固体接触传导层，为发展稳定的､可靠的固态聚合物膜离子选择性电极开辟了一条新的研究思路。 (1) 基于纳米材料的固体接触传导层大多采用多次滴涂的方式，该操作繁琐、耗时，厚度不宜控制，而且与导电基体的弱粘着力也影响固态离子选择性电极的发展。基于此，采用电化学合金/去合金方法在金电极表面原位形成了纳米多孔金膜，并利用其大的比表面积、良好的导电性和大的双电层电容等特点将其作为新的固体接触传导层，发展了固态K+离子选择性微型电极。该电极的线性范围为1.0×10-6 - 1.0×10-2 M，响应斜率为54.2 mV/s，检出限为4.0×10-7 M。与涂丝电极相比，该电极具有良好的电位稳定性。区别于其他额外材料作为单次使用的固体接触传导层，纳米多孔金固体接触传导层是原位形成的，可重复使用。另外，通过改变膜组分中离子载体有望发展固态离子选择性微型电极用于重金属离子的测定。 (2) 为了能够有效阻止离子载体从膜相中缓慢渗漏，发展了很多离子载体固定方法，如将离子载体共价固定在聚合物骨架上、将离子载体固定在纳米材料(如金纳米颗粒和碳纳米管等)上等。然而，这些方法存在选择性变差、合成复杂、操作成本高、分散性不好等问题。基于此，合成了十八烷基功能化石墨烯(GO-ODA)，并将其分散在Ca2+离子选择性敏感膜中制备固态Ca2+离子选择性电极。GO-ODA的使用一方面是作为传导元件改善固态Ca2+离子选择性电极的稳定性，另一方面是基于烷基链-烷基链疏水作用固定Ca2+离子载体，减缓离子载体的渗漏。所发展电极的线性范围为3.0×10-7 - 1.0×10-3 M，电极检出限为1.6×10-7 M。由于GO-ODA复合物良好的疏水性和电子导电性，该电极具有良好的电位稳定性，并且无水层干扰。 3. 发展非聚合物膜固态离子选择性电极 聚合物膜离子选择性电极的研究已开展数十年，在临床医学、工业分析、和环境监测分析领域取得了可喜的成绩。然而，其在实际应用中存在一些潜在的不足之处，比如实际样品中亲脂性物质很容易萃取进入聚合物膜相，进而干扰电极的电位响应性能等。因此，需要发展一些非聚合物膜固态离子选择性电极。 (1) 市售的固态Cu2+离子选择性晶体膜电极已用于饮用水和海水中Cu2+的测定。其制备方法是将CuS和Ag2S混合后在高压(约4.9×108 Pa)下制成厚度约为1-2 mm致密薄片，经抛光处理后组装成电极。这类型电极存在制备条件苛刻、获得的薄片易碎等缺点。基于此，制备了CuS纳米颗粒功能化石墨烯，发展了非聚合物膜Cu2+离子选择性电极。所发展电极的线性范围为1.0×10-7 - 1.0×10-3 M，检出限为6.7×10-8 M。该电极表现出良好的选择性和可逆性。该电极的制备为发展固态Cu2+离子选择性电极提供了一种简单、可行的方法。 (2) 核酸中碱基T(胸腺嘧啶)能特异性的与Hg2+形成T-Hg-T配合物，而其他金属离子几乎不与胸腺嘧啶分子结合。因此，很多富含T的寡聚DNA汞离子探针相继被开发出来。但这种核酸类探针存在一定的缺陷，比如合成复杂、稳定性差、测定条件要求严苛等。基于此，将胸腺嘧啶掺杂在聚吡咯中制备了非聚合物膜固态Hg2+选择性电极，开发了耐用的测定Hg2+的电位型传感器。所发展的电极的线性范围为1.0×10-6 -1.0×10-3 M，响应斜率为79.0 mV/dec，检出限为7.9×10-7 M，响应时间 > 10 min。该非聚合物膜固态离子选择性电极响应不符合传统能斯特响应，不同于传统聚合物膜离子选择性电极的响应。
英文摘要	Compared to the conventional liquid-contact ion-selective electrodes (ISEs) with inner filling solutions, all-solid-state ISEs don’t suffer from the steady-state primary ion fluxes from the organic sensing membranes into the aqueous surface layers, due to the absence of the inner filling solutions. They also have several advantages, such as convenient storage and maintenance, durability, easy miniaturization and ease of the electrode orientation handling, which make all-solid-state ISEs favorable for developing environmental monitoring methods and monitoring techniques. However, due to the high charge-transfer resistance, the low double layer capacitance and the presence of the water layer at the interface between the ion selective membrane and the electronic conductor, the poor potential stabilities of all-solid-state ISEs limit their further developments. Moreover, the slow leaching of the membrane components, especially for ionophores, and the extraction of the lipophilic components from the practical samples into the polymer membranes are also of concern. This dissertation reports a series of all-solid-state ISEs in order to improve the potential stability, prevent the leakage of ionophores and eliminate the interference of lipophilic components. The detail contents are as follows: 1. Applying and improving the conducting polymer-based solid contacts Conducting polymers are electronically conducting materials that can form an ohmic contact on various kinds of electronic conductors, such as carbon, gold and platium, through the electrodeposition or drop-casting method. Additionally, conducting polymers are electroactive materials with mixed electronic and ionic conductivity, and they can transduce an ionic signal into an electronic one. Based on these properties, conducting polymers have been widely used as ion-to-electron transducers. (1) The physicochemical properties of polypyrrole are significantly influenced by the doping ions. Compared to polypyrrole doped with other ions (eg. ClO4-), Nafion doped polypyrrole is reported to have improved mechanical robustness and electrochemical stability. Thus, an all-solid-state polymeric membrane Pb2+-selective electrode is developed based on Nafion doped polypyrrole as ion-to-electron transducer. The introduction of Nafion in polypyrrole not only improves the performances of conducting polymer-based solid contact, including the redox capacitance and the adhesion to ion-selective membrane, but also eliminates the influence of water layer on the potential stability through the hydrophobic backbones. The proposed Pb2+-selective electrode shows a stable Nernstian response within the concentration range of 1.0×10-7 - 1.0×10-3 M. The detection limit calculated as the intersection of the two slope lines is 4.0×10-8 M. The response time is less than 10 s. The all-solid-state Pb2+-selective electrode displays considerable potential stability, and no undesirable water layer is formed between Nafion doped polypyrrole-based solid contact and the Pb2+-selective polymeric membrane. (2) Poly(3-octylthiophene) (POT) represents a conjugated polymer with a relatively high oxidation potential. Compared to polypyrrole, POT has a low electroactivity, electronic conductivity and redox capacitance. It may not participate in electrochemical side reactions during the ion-to-electron transduction process to the same extent as the highly p-doped conducting polymers, such as polypyrrole. Additionally, POT is highly lipophilic, which may effectively prevent the formation of an internal water layer between the electronic substrate and ion-selective membrane. Moreover, POT is reported to show interact with Ag+ through the sulfur atoms and double bonds. Thus, a single-piece all-solid-state Ag+-selective electrode is developed based on POT dissolved into Ag+-selective membrane. POT in the ion-selective membrane not only recognizes Ag+ together with ionophore, but also is used as ion-to-electron transducer to improve the potential stability. The proposed electrode shows a stable potential response in the linear range of 3.0×10-8 - 3.0×10-5 M with a detection limit of 1.9×10-8 M. The single-piece all-solid-state Ag+-selective electrode exhibits a considerable potential stability, no significant redox sensitivity and no water layer formed between the glassy carbon electrode and the ion-selective membrane. The electrode is used for the potentiometric titration of chloride and determination of Ag+ concentrations in spiked waters.   2. Developing new types of nanomaterial-based solid contacts Conducting polymers, including polypyrrole, poly(3-octylthiophene) and poly(3,4-ethlyenedixythiophene), are commonly used as ion-to-electron transducer materials. However, these materials suffer from some limitations during the ion-to-electron transduction processes, such as light sensitivity, remnants of salt from the polymerization process, undesired side reactions with redox interferences and sensitivity to dissolved oxygen and CO2. Recently, nanomaterials, including fullerene, three-dimensionally ordered macroporous carbon, carbon nanotubes, graphene and Au clusters, etc, have been widely applied as solid contacts, due to their large surface area/volume ratio, good conductivity and hydrophobicity. This opens a new way for developing stable and reliable all-solid-state polymeric membrane ISEs. (1) Multilayer drop-casting methods are commonly used to prepare nanomaterial-based solid contacts. Not only the preparation process is tedious, time-consuming and not easy to control the thickness, but also the weak adhesion on the electronic conductors would influence the development of all-solid-state polymeric membrane ISEs. Thus, an all-solid-state polymeric membrane K+-selective miniaturized electrode is developed based on a nanoporous gold film as solid contact. The nanoporous gold film, which is in-situ formed on the surface of a gold wire electrode by the multicyclic electrochemical alloying/dealloying method, shows large surface area, high double layer capacitance and good conductivity. The proposed electrode shows a stable potential response in the linear range of 1.0×10-6 - 1.0×10-2 M with a slope of 54.2 mV/dec and a detection limit of 4.0×10-4 M. The all-solid-state K+-selective electrode shows an improved potential stability in comparison with the coated-wire K+-selective electrode. Unlike the additionally coated intermediate layers as single-use solid contacts, the in-situ formed nanoporous gold film as solid contact is reusable. All-solid-state polymeric membrane ion-selective miniaturized electrode for the detection of heavy metal ions are hopefully developed through changing the ionophores in the ion-selective membranes. (2) In order to avoid the loss of ionophores from the ion-selective membrane, many methods for the immobilization of ionphores have been proposed, such as the covalent immobilization of them to polymer backbones, the immobilization of them on nanomaterials (eg. gold nanoparticles and carbon nanotubes). However, these methods suffer from the deterioration of selectivity, the complex synthetic process, high operation cost and poor dispersion. Thus, an all-solid-state polymeric membrane Ca2+-selective electrode is developed based on hydrophobic octadecylamine-functionalized graphene oxide (GO-ODA) dissolved into Ca2+-selective membrane. The GO-ODA composite in the ion-selective membrane not only acts as a transduction element to improve the potential stability for the all-solid-state Ca2+-ISEs, but also is used to immobilize Ca2+ ionophore with lipophilic side chain through hydrophobic interactions in order to slow down the leaching process of ionophore. The proposed electrode shows a stable Nernstian response in the linear range of 3.0×10-7 - 1.0×10-3 M with a detection limit of 1.6×10-7 M. Additionally, due to the hydrophobicity and the electrically conductivity of the GO-ODA composite, the proposed GO-ODA-based electrode exhibits an improved stability with the absence of water layer between the ion-selective membrane and the glassy carbon electrode. 3. Developing all-solid-state non-polymeric membrane ion-selective electrodes Polymeric membrane ion-selective electrodes have been developed for several decade years and have gained great achievements for determination of ionic species in clinical, industrial and environmental analysis. However, there are some underlying limitations for practical applications. For example, the potential responses for the polymeric membrane ion-selective electrodes are greatly influenced by the extraction of the lipophilic components from the practical samples into the polymer membranes. Therefore, it’s necessary to develop some non-polymeric membrane ion-selective electrodes. (1) Commercially available solid-state Cu2+-ISEs based on jalpait (coprecipitated CuS/Ag2S) membranes have been applied for determining Cu2+ in drinking water and seawater. The preparation process is that the mixtures of CuS and Ag2S are pressed into thin slices with the thickness of 1 - 2 mm under high pressure (about 4.9×108 Pa), and the electrodes are assembled after polishing treatment. Such electrodes need rigorous preparation requirement, and the slices are very fragile. Thus, an all-solid-state non-polymeric membrane Cu2+-selective electrode is developed based on CuS decorated graphene composite. Based on the dissociation reaction of CuS, the proposed electrode shows a stable potential response in the linear range of 1.0×10-7 - 1.0×10-3 M with a detection limit of 6.7×10-8 M. The all-solid-state non-polymeric membrane Cu2+-selective electrode shows good selectivity and reversibility. This work provides a easy and feasible method for fabricating all-solid-state non-polymeric membrane Cu2+-ISEs. (2) Thymine-Hg2+-thymine complexes are formed through the specific binding of thymine bases in nucleic acid to Hg2+. The binding reactions of thymine bases to other heavy metal ions hardly occur. Therefore, many thymine base-riched DNA probes have been developed for detection of Hg2+. However, such probes suffer from some limitations, such as complex preparation procedures, poor stability and rigorous measurement conditions. Thus, a durable all-solid-state non-polymeric membrane Hg2+-selective electrode is developed based on thymine doped polypyrrole. The proposed electrode showed a stable potential response in the linear range of 1.0×10-6 - 1.0×10-3 M with a slope of 79.0 mV/dec and a detection limit of 7.9×10-7 M. The response time is more than 10 min. The potential responses of the all-solid-state non-polymeric membrane Hg2+-selective electrode don’t conform to Nernst equation, which are different from those of the conventional polymeric membrane ion-selective electrodes.
语种	中文
学科主题	化学 ; 分析化学 ; 环境科学技术基础学科
内容类型	学位论文
源URL	[http://ir.yic.ac.cn/handle/133337/8340]
专题	中科院烟台海岸带研究所知识产出_学位论文
作者单位	中科院烟台海岸带研究所
推荐引用方式 GB/T 7714	尹坦姬. 基于导电聚合物和纳米材料的固态离子选择性电极的研究[D]. 北京. 中国科学院研究生院. 2015.

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